what is the function of the skeletal system
-structural support
-protection
-mineral storage
-blood cell production
-leverage
what is the difference between cortical and trabecular bone
cortical is compact boen while trabecular is spongy bone
what are the different shapes of bones
long, flat, short and irregular
what is the ends of the bone called and what is the shaft called
ends are epiphyses and the shaft is the diaphysis
what is the growth plate called
epiphyseal plate when you get older its called the epiphyseal line
what is the central cavity called
medullary cavity
what is the difference between periosteum and endosteum
-periosteum covers the diaphysis
-endosteum lines the medullary cavity
what does the central (haversian) canal contain
has blood vessels, nerve supply and is lined with endostium
what provides channels for blood vessels in the central canal to connect with blood vessels in the periosteum
perforating canal
what is a osteon, what does it have, where is it found
-this is the functional unit of the bone
-consists of lamellae and central canal
-it is found in compact bone
what are the 2 layers of periosteum and what does it allow
-fibrous outer layer and cellular layer
-it allows tendons/ligaments to attach
what are the different parts of the osteon and what is its function
-lacuna: tiny cavity that houses ostecoytes
-lamella: a thin layer of matric in concentric arrangments around the lacunae
-osteocyte: bone cell derived form osteoblast
-canaliculi: passageway that extend the launch into the lamellae and provides a passageway for nutrients and waste
what are the different types of bone cells and what they do
-osteoprogenitor cell: it is a stem cell and can divide into osteoblast
-osteoblast: premature bone cell in the periosteum, secretes collagen and builds bone
-osteocyte: mature bone cell in the lacunae, important for bone turnover and repair
-osteoclast: multinucleated and resopriton of bone
what are the steps for intramembranous ossification
- mesenchymal cells differentiate into osteogenic cells
- osteogenic cells become osteoblast and ghater to become the ossification center
- osteblasts secrete unmieneralized material called osteoid, this allows collagen/mineral deposition and the tissue hardens
- osteoblasts trapped by the hardened matric become osteocytes
- osteogenic cells in the surrounding connective tissue differentiate into osteoblasts at the edges
- if there is capilaries there the bone becomes spongy bone
- compact bone is formed superficial to spongy bone
what are the steps for endochondral ossfiication
- mesenchymal cells differentiate into chondrocytes that produce cartilage template for bone
- blood vessels on the edge of the cartilage model bring osteoblasts that deposit bony layer
- capillaries penetrate cartilage and deposit bone inside the cartilage model and make primary ossification center
- cartilage and chondrocytes keep growing at the ends of the bone while the medullary cavity expands and remodels
- secondary ossification center develop after birth
- hylaine cartilage reids at epiphyseal plate and at joint surface as articular cartilage until the end of puberty
do bones remodel even after they done growing
yes
when do bones remodel
-when Ca2+ concnetratoin changes
-there is mechanical stress applied to bone
how much of the bodys calcium, phospate and carbonate do bones store
99%
what is Paget’s disease
-this is where osteoclast activity is higher than osteoblast activity
-causes weak and brittle bones that are miss shapen and prone to fracture
what is rickets disease and what causes it
-happens in children where bones don’t calcify, they are soft and weight-bearing bones will become bowed
-lack of Ca2+ or vitamin D
what do you T score need to be for osteopenia and osteoporosis
osteopenia: -1 to -2.5
osteoporosis: anything greater than -2.5
